On the Origin of High-Altitude Open Clusters in the Milky Way

Martinez-Medina, L. A.; Pichardo, B.; Moreno, E.; Peimbert, Antonio; Velázquez, Héctor

doi:10.3847/2041-8205/817/1/l3

Cited by 20 publications

(22 citation statements)

References 29 publications

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“…Thus, our approach may have an impact on the identification of dynamical signatures of resonant orbits and on the degree of chaos in the solar neighbourhood, and on its local phase-space structure (Chakrabarty 2007;Chakrabarty & Sideris 2008). It may also shed light on the origin of kinematic moving groups, believed to be related to resonances (Antoja et al 2008(Antoja et al , 2009(Antoja et al , 2011Moreno et al 2015;Martinez-Medina et al 2016). These topics, as well as a dynamical analysis of three-dimensional potentials, will be the subject of a forthcoming study.…”

Section: Discussionmentioning

confidence: 93%

Modelling resonances and orbital chaos in disk galaxies

Michtchenko

Vieira

Barros

et al. 2016

A&A

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Context. Resonances in the stellar orbital motion under perturbations from the spiral arm structure can play an important role in the evolution of the disks of spiral galaxies. The epicyclic approximation allows the determination of the corresponding resonant radii on the equatorial plane (in the context of nearly circular orbits), but is not suitable in general. Aims. We expand the study of resonant orbits by analysing stellar motions perturbed by spiral arms with Gaussian-shaped groove profiles without any restriction on the stellar orbital configurations, and we expand the concept of Lindblad (epicyclic) resonances for orbits with large radial excursions. Methods. We define a representative plane of initial conditions, which covers the whole phase space of the system. Dynamical maps on representative planes of initial conditions are constructed numerically in order to characterize the phase-space structure and identify the precise location of the co-rotation and Lindblad resonances. The study is complemented by the construction of dynamical power spectra, which provide the identification of fundamental oscillatory patterns in the stellar motion. Results. Our approach allows a precise description of the resonance chains in the whole phase space, giving a broader view of the dynamics of the system when compared to the classical epicyclic approach. We generalize the concept of Lindblad resonances and extend it to cases of resonant orbits with large radial excursions, even for objects in retrograde motion. The analysis of the solar neighbourhood shows that, depending on the current azimuthal phase of the Sun with respect to the spiral arms, a star with solar kinematic parameters (SSP) may evolve in dynamically distinct regions, either inside the stable co-rotation resonance or in a chaotic zone. Conclusions. Our approach contributes to quantifying the domains of resonant orbits and the degree of chaos in the whole Galactic phase-space structure. It may serve as a starting point to apply these techniques to the investigation of clumps in the distribution of stars in the Galaxy, such as kinematic moving groups.

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Section: Discussionmentioning

confidence: 93%

Modelling resonances and orbital chaos in disk galaxies

Michtchenko

Vieira

Barros

et al. 2016

A&A

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“…Numerical simulations of open cluster orbital evolution have shown that it is possible for the spiral arms of the Galaxy to have a large vertical effect on clusters, giving them large out-of-plane excursions (>200 pc), though these orbits tend to be chaotic (see e.g., Martinez-Medina et al 2016). Martinez-Medina et al (2017) investigated the survival of such high-altitude open clusters, and find that clusters in the plane of the disk and clusters with relatively large vertical motions (z max 3.5 kpc) tend to have the longest lifetimes.…”

Section: Orbitmentioning

confidence: 99%

“…It is therefore surprising to find Gaia 1 in its present orbit at the present day. This suggests that either it has recently moved into this orbit, perhaps after an interaction with a spiral arm (Martinez-Medina et al 2016), or that it has experienced significant mass loss in the past, and is now on the verge of complete destruction. Significant mass loss in the past would tend to support the association of the extratidal stars we find with radial velocities, metallicities and photometry consistent with Gaia 1.…”

Section: Orbitmentioning

confidence: 99%

Siriusly, a newly identified intermediate-age Milky Way stellar cluster: a spectroscopic study of Gaia 1

Simpson

Silva

Martell

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We confirm the reality of the recently discovered Milky Way stellar cluster Gaia 1 using spectra acquired with the HERMES and AAOmega spectrographs of the Anglo-Australian Telescope. This cluster had been previously undiscovered due to its close angular proximity to Sirius, the brightest star in the sky at visual wavelengths. Our observations identified 41 cluster members, and yielded an overall metallicity of [Fe/H] = −0.13 ± 0.13 and barycentric radial velocity of v r = 58.30 ± 0.22 km/s. These kinematics provide a dynamical mass estimate of 12.9 +4.6 −3.9 × 10 3 M . Isochrone fits to Gaia, 2MASS, and Pan-STARRS1 photometry indicate that Gaia 1 is an intermediate age (∼ 3 Gyr) stellar cluster. Combining the spatial and kinematic data we calculate Gaia 1 has a circular orbit with a radius of about 12 kpc, but with a large out of plane motion: z max = 1.1 +0.4 −0.3 kpc. Clusters with such orbits are unlikely to survive long due to the number of plane passages they would experience.

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“…In a previous work (Martinez-Medina et al 2016a), we showed that a mechanism able to lift open clusters way up the Galactic plane are the spiral arms. The presence of the spiral arms induces several clusters to be violently lifted from the Galactic plane, to heights up to 3 kpc.…”

Section: Survival Of Lifted Clustersmentioning

confidence: 91%

“…In Figure 6 we show the mass evolution, as well as the orbits, for three examples of lifted clusters from the work by Martinez-Medina et al (2016a). The blue lines indicate the life stage of the cluster when it moves confined to the Galactic plane; the red lines indicate the second part of its evolution: when the cluster oscillations take it away from the plane, crossing the disk.…”

Section: Survival Of Lifted Clustersmentioning

confidence: 99%

On the Survival of High-Altitude Open Clusters Within the Milky Way Galaxy Tides

Martinez-Medina

Pichardo

Peimbert

et al. 2017

ApJ

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It is a common assumption that high-altitude open clusters live longer compared with clusters moving close to the Galactic plane. This is because at high altitudes, open clusters are far from the disruptive effects of in-plane substructures, such as spiral arms, molecular clouds and the bar. However, an important aspect to consider in this scenario is that orbits of high-altitude open clusters will eventually cross the Galactic plane, where the vertical tidal field of the disk is strong. In this work we simulate the interaction of open clusters with the tidal field of a detailed Milky Way Galactic model at different average altitudes and galactocentric radii. We find that the life expectancy of clusters decreases as the maximum orbital altitude increases and reaches a minimum at altitudes of approximately 600 pc. Clusters near the Galactic plane live longer because they do not experience strong vertical tidal shocks from the Galactic disk; then, for orbital altitudes higher than 600 pc, clusters start again to live longer due to the decrease in the number of encounters with the disk. With our study, we find that the compressive nature of the tides in the arms region and the bar have an important role on the survival of small clusters by protecting them from disruption: clusters inside the arms can live up to twice as long as those outside the arms at similar galactocentric distance.

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On the Origin of High-Altitude Open Clusters in the Milky Way

Cited by 20 publications

References 29 publications

Modelling resonances and orbital chaos in disk galaxies

Modelling resonances and orbital chaos in disk galaxies

Siriusly, a newly identified intermediate-age Milky Way stellar cluster: a spectroscopic study of Gaia 1

On the Survival of High-Altitude Open Clusters Within the Milky Way Galaxy Tides

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